Electronic driving-aids, such as adaptive cruise control arrangements, have become increasingly present in today's cars. An adaptive cruise control arrangement is an arrangement that is configured to automatically adjust vehicle speed to maintain a proper distance from vehicles ahead. In many cases such arrangement makes use of sensor information from on-board sensors.
Driving in urban environments adds requirements on driving aids, such as adaptive cruise control arrangements, since urban driving environments often comprise various driving speeds of surrounding vehicles, a lot of intersections, traffic lights, etc. A conventional adaptive cruise control arrangement is usually configured to control host vehicle velocity based on a distance to a preceding vehicle and a velocity of the preceding vehicle. Such a conventional adaptive cruise control arrangement will not be able to control host vehicle velocity in a satisfactory manner when following a preceding vehicle driving in a roundabout. One reason is that such a conventional adaptive cruise control arrangement may lose track of the preceding vehicle when the preceding vehicle is in a roundabout, due to the relatively large lateral movement of the preceding vehicle when it drives in the roundabout. When it loses track of the preceding vehicle, it will not be able to regulate host vehicle velocity in a satisfactorily manner. Thereby, such a conventional adaptive cruise control arrangement will usually not be able to control host vehicle velocity in a pleasant and/or safe manner.
To summarize, it is an advantage if driving aids, such as adaptive cruise control arrangements, are provided with information constituting reliable interpretations of a driving environment.
The document GB 2397398 B relates to an adaptive cruise control device for a vehicle including a detector connected to various vehicle sensors for detecting a current potentially hazardous driving condition. Examples of potentially hazardous driving conditions as specified in GB 2397398 B are; use of a telephone, use of a navigation system, approaching a T junction or roundabout. It is specified in GB 2397398 B that the roundabout is detected by the vehicle's navigation system. Such a device is associated with a number of drawbacks. One such drawback is that it will be dependent upon updated map information and access to signals from a number of satellites.
In view of the above, there is a need for an improved roundabout detecting arrangement which overcome at least some of the above mentioned drawbacks.